[HCDX] Field coils in speakers

["Robert Foxworth" <rfoxwor1@xxxxxxxxxxxxxxx>]

 Speakers have a voice coil and the signal flows through it. Today the voice
coil is placed in the field of a permanent magnet at the rear of the
speaker.
The magnetic field makes the voice coil move back and forth which generates
the sound. The voice coil is part of the paper cone assembly, which actually
makes the sound when it moves.

Back then, there was also a field coil, instead of the magnet. The radio B+
voltage
flowed through the field coil which generated the magnetic field and also
acted as the filter choke in the power supply. Although there were 4 wires
then,
your guess is essentially correct. You hit the wrong wire!  This was
typically
250 volts DC. You were lucky...

(Age test ... who under age 40 knows what this is all about, hi)

73 Bob Foxworth

> 1. We lived in Burbank, CA, and used to have a large Silvertown console
> radio in the hall between my bedroom and my sister's (it used to be in the
> living room until we got our first TV). I had found an old cloth aviator's
> helmet with earphones while I was on my paper route in 1952 or 53. I was
13
> and figured out how to hook them in parallel with the console's speaker
> though I got some bad shocks while doing it (I wonder if the B+ flowed
> through the speaker's line?). In those days, >

> Phil Finkle, K6EID (ex SWL-W6)
>


---[Start Commercial]---------------------
World Radio TV Handbook 2002 will be out soon!
You can get yours for $17.46 + shipping + possible tax in some states.
Please visit: http://www.amazon.com/exec/obidos/ASIN/0823059332/hardcoredxcom
And while you buy it, you'll also support Hard-Core-DX. Thank you.
---[End Commercial]-----------------------
________________________________________
Hard-Core-DX mailing list
Hard-Core-DX@xxxxxxxxxxxxxxxx
http://www2.hard-core-dx.com/mailman/listinfo/hard-core-dx
http://www.hard-core-dx.com/
_______________________________________________

THE INFORMATION IN THIS ARTICLE IS FREE. It may be copied, distributed
and/or modified under the conditions set down in the Design Science License
published by Michael Stutz at http://dsl.org/copyleft/dsl.txt